Description

A combined preparation containing two synthetically obtained thyroid hormones: levothyroxine (T4) and liothyronine (T3), which increase basal metabolism, accelerate carbohydrate, fat and mineral metabolism, influence bone tissue metabolism, growth and maturation, oxygen consumption, heart function, circulatory system and brain. They have a strong influence on the biosynthesis, peripheral metabolism or mechanism of action of other hormones. In peripheral tissues, T4 is converted to T3, which is the actual metabolically active hormone. Levothyroxine sodium taken orally on an empty stomach is absorbed by up to 80%, liothyronine by 78-95%, mainly from the small intestine. The onset of action of levothyroxine occurs after 3-5 days. Both bind to plasma proteins, but T3 binds less strongly than T4. Thyroid hormones are metabolized mainly in the liver, kidneys, brain and muscles. T0.5 is approximately 24 hours for T3, and 7 days for T4. In hyperthyroidism, the half-life is shortened and in hypothyroidism, it is prolonged